Spinning device for spinning molten polymers and method for heating the spinning device

ABSTRACT

The invention relates to a spinning device in which liquid polymer is guided through a polymer line with a first heating jacket to a spinning pump with a second heating jacket. From said spinning pump, the polymer is transported through several lines to spinning packets and extruded through spinnerts to form filaments. The lines that are connected downstream of the spinning pump, the spinning packets and the spinnerets are located in at least one spinning housing through which heating fluid flows. There is a distance of 5 mm between the spinning housing through which the heating fluid flows and the first and second heating jackets and the spinning pump, to obtain thermal decoupling. According to a method for heating the spinning device, vaporous heating fluid is guided out of a first reservoir into the spinning housing, and heating fluid is guided out of a second reservoir into the first and/or second heating jacket. The temperature of the heating fluid that is supplied to the spinning housing is 10 to 40° C. higher than the temperature of the heating fluid that is supplied to the first and/or second heating jacket.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage of PCT/EP00/03974 filed 2 May 2000and is based upon German national application 199 24 838.9 of 29 May1999 under the International Convention.

FIELD OF THE INVENTION

The invention relates to an apparatus for spinning liquid polymers toproduce polymer filaments, whereby the liquid polymer flows through apolymer duct with a first heating jacket to a spinning pump with asecond heating jacket, which displaces the polymer through a pluralityof conduits to spinning packets and extrudes the polymer through thespinneret downwardly to form filaments, whereby the conduits downstreamof the spinning pump, the spinning packets and the spinneret are locatedin at least one spinning housing that is traversed by heating fluid. Theinvention also relates to a method of heating the spinning apparatus.

BACKGROUND OF THE INVENTION

Spinning apparatuses with heating of this type are known from DE 196 24946 A1 and DE 198 09 495 A1. The different. heated parts of theapparatus are maintained, in this case, approximately at the sametemperature level which is prescribed by the heating fluid used.

OBJECT OF THE INVENTION

The invention has as its object to maintain the molten polymer upstreamof the spinning housing, independently of the temperature in thespinning housing, at the lowest possible temperature so as to excludepossible damage to the polymer.

SUMMARY OF THE INVENTION

According to the invention the object is attained in the spinningapparatus described at the outset in that between the spinning housingtraversed by the heating fluid on the one hand and on the other hand thefirst and second heating jackets and the spinning pump, there is aspacing of at least 5 mm and preferably at least 10 mm. This spacingensures a thermal decoupling and ensures that the polymer will be heldat the lowest possible temperature as long as it has still not enteredthe heated spinning housing. In this manner deterioration in the flowingpolymer, which can arise as a result of relatively high temperatures,can be completely or largely excluded.

In addition to a spatial separation of the heated spinning housing, itis advantageous in accordance with a further feature of the invention toeffect the heating of the spinning apparatus in a suitable manner. Forthis purpose heating fluid in the form of a vapor is conducted from afirst supply vessel into the spinning housing and heating fluid from thelater is discharged, heating fluid from a second supply vessel is fedthrough the first and/or second heating jackets, and care is taken suchthat the temperature of the heating fluid in a vapor state fed to thespinning housing is 10 to 40° C. higher than the temperature of theheating fluid that is fed to the first and/or second heating jackets.

The heating fluids can be prepared with different temperatures in twosupply vessels. As a heating fluid, for example Diphyl, is suitable andis commercially available in various modifications whereby the sameheating fluid or different heating fluids can be prepared in the twosupply vessels. To maintain the temperature difference on the one handin the region of the spinning pump and the polymer feed conduits and onthe other hand in the spinning housing, the region between the spinninghousing on the one hand and the first and second heating jackets on theother hand can be maintained free from the heating fluid. As a resultthe desired temperature difference can be maintained during operation.

The supply of heating fluid to the first and second heating jackets canbe coupled in many cases; thus it is possible to feed the heating fluidcoming from the supply vessel initially through the first heating jacketand then through the second heating jacket or in the reverse order.Usually the first and second heating jackets are heated with liquidheating fluid. It is further possible to operate the first and secondheating jackets also with separate heating circulations.

As the polymer one can use for example polyester or polyamide. Theliquid polymer usually derives from an extruder for the melting ofpolymer granules but, however, can be from a polymerization reactor. Thepolymer is admitted to the region of the spinning pump at a temperatureof 270 to 300° C. and is extruded through the spinneret with atemperature of about 295 to 320° C.

BRIEF DESCRIPTION OF THE DRAWING

Various possible embodiments of the apparatus and method are detailedwith the aid of the drawing wherein:

FIG. 1 is a schematic illustration of the spinning device;

FIG. 2 is a similar cross sectional view showing one variant for thesupply of heating fluid; and

FIG. 3 is another section showing a second variant of the supply ofheating fluids to the spinning device.

SPECIFIC DESCRIPTION

The main parts of the spinning device according to FIG. 1 are thespinning housing 1 which is also designated as a spinning beam, with aplurality of spinning packets 2 and spinnerets 3, the spinning pump 4and the extruder or polymerization reactor 5 from which the liquidpolymer flows through a duct 6 to the pump 4. From there, the polymer isfed through outlet conduits 7 of which only one has been illustrated,into spinning packets 2. The spinning housing 1 has a heating chamber 8which is heated in the usual manner with a heating fluid in the form ofvapor. The heating jacket and also the heating chamber 8 are providedwith inlet and outlet ducts for heating fluid; in FIGS. 2 and 3 theseare indicated in greater detail. The outlet conduits 7 pass through thesupport 12 forming the region maintained free from the heating fluidmentioned earlier.

In the duct 6 a pump 10 can be provided when the polymer does not comefrom an extruder but derives from a polymerization reactor 5. Theheating of the spinning housing 1, the region of the spinning pump 4 andthe duct 6 can be effected in different ways largely independent fromone another since heating fluid in a first supply vessel 14 and a secondsupply vessel 15 can be prepared with different temperatures (compareFIGS. 2 and 3).

In a first variant (compare FIG. 2), which is especially suitable forpolyester, the liquid polymer derives from a polymerization reactor 5 atabout 278° C. Via the pump 10 (for example a gear pump), the melt is fedthrough the feed duct 6 initially to the spinning pump 4 and from thereto the spinneret 3 where the melt is extruded downwardly in the form ofnumerous filaments 16. In a manner known per se and not illustrated ingreater detail (compare also FIG. 1), the filaments travel through ashaft 17 downwardly to a coiling device. Heating fluid in the form of avapor, whose temperature is slightly above the boiling point, derivesfrom the first vessel 14 and flows through the conduit 9 into theheating chamber 8 and then through the conduit 18 into the secondheating jacket 4 a. From there the vapor flows through the conduit 19into a condenser 20. Condensed heating fluid flows through the conduit21 back into the first heating vessel 14 where it is reheated. Thetemperature in the conduit 9 usually lies in the range of 280 to 330° C.At the same time heating fluid from the second supply vessel 15 which ispreferably liquid, is fed through the conduit 23 to the first heatingjacket 6 a and flows by the return conduit 24 back into the secondsupply vessel 15.

A further heating variant is detailed with the aid of FIG. 3. Here thepolymer derives from an extruder 5 in which preferably polyester andpossibly also polyamide is processed. A heating medium in the form ofvapor is fed through the conduit 9 into the heating chamber 8 and fromthere through the conduit 22 directly into the condenser 20 and fromthere back. From the second supply vessel 15 comes heating fluid whichis preferably liquid and traverses the conduit 25 to enter initially thesecond heating jacket (4 a) and from there flows through the conduit 26into the first heating jacket 6 a. The return line is provided by theconduit 24.

EXAMPLE

Polyester is spun and Diphyl is used as the heating fluid both in thefirst supply vessel 14 as well as in the second supply vessel 15. Thedistance between the heated spinning housing 1 and the cold region ofthe two heating jackets and the spinning pump 4 amounts to 20 mm.

Eample 1

The operation is in accordance with FIG. 2 whereby the polymer derivesfrom the reactor 5 at a temperature of 278° C. The heating fluid fromconduit 23 has a temperature of 280° C. The temperature in the region ofthe spinneret 3 amounts to 310° C. and the heating fluid vapor has thesame temperature in the conduit 9 and 18. In the outlet conduit 7 thetemperature amounts of 196° . The temperature increase in the polymerresulting from the pressure increase by the spinning pump 4 amounts to14° C. and the pump 10 raises the temperature of the polymer by 20° C.

Eample 2

The operation is in accordance with FIG. 3 whereby the polymer derivesfrom the extruder 5 at 295° C., the temperature being 310° C. in theregion of the spinneret 3. The temperature increase in the polymerresulting from the pressure increase by the spinning pump 4 amounts to14° C. The heating fluid in the conduit 9 has a temperature of 315° C.and in the conduits 25 and 26 of 298° C.

What is claimed is:
 1. An apparatus for the spinning of liquid polymerto produce polymer filaments where the liquid polymer flows through apolymer duct with a first heating jacket to a spinning pump with asecond heating jacket, which displaces the polymer through a pluralityof conduits to spinning packets and which is then extruded throughspinnerets downwardly to form filaments, whereby the conduits downstreamof the spinning pump, the spinning packets and the spinnerets aredisposed in at least one spinning housing which is traversed by aheating fluid in the form of a vapor, a distance of at least 5 mm beingprovided between the spinning housing traversed by the heating fluid onthe one hand and the first and second heating jackets and the spinningpump on the other hand, a heating fluid from a second supply beingadmitted into the first heating jacket, and the temperature of theheating fluid in the form of a vapor supplied to the spinning housing is10 to 40° C. higher than the temperature of the heating fluid that isfed to the first heating jacket, the second heating jacket, whichsurrounds the spinning pump, being fed with heating fluid from thespinning housing.
 2. A method of heating a spinning apparatus comprisingthe steps of: (a) passing a liquid polymer flow through a polymer ducthaving a first heating jacket to a spinning pump having a second heatingjacket and from said spinning pump into a housing containing at leastone spinning packet provided with a spinneret and a conduit deliveringsaid liquid polymer flow to said spinning packet; (b) passing at leastone heating fluid through said first and second jackets and through saidhousing; (c) maintaining a spacing between said housing and an assemblyconsisting of said first and second heating jackets and said spinningpump of at least 5 mm; (d) providing the heating fluid supplied to saidhousing as a vapor and at a temperature 10 to 40° C. above thetemperature of heating fluid supplied to said first heating jacket andsaid second heating jacket; and (e) feeding heating fluid from saidhousing through said second heating jacket.
 3. The method defined inclaim 2 wherein the heating fluid provided to said housing is suppliedat a temperature in the range of 280° C. to 330° C.